The present invention relates to wireless communication systems. More particularly, the present invention relates to optimizing available resources in wireless communication systems.
Wireless communication systems typically use a Broadcast Channel (BCH) to communicate control information to facilitate communications between wireless transmit/receive units (WTRUs) and the system. For example, the BCH is used to communicate to WTRUs information regarding the Radio Access Network (RAN) as well as information specific to the cell, even before the WTRUs are connected. In Time Division Duplex (TDD) type systems, for example, the BCH is transmitted on the Primary Common Control Physical Channel (PCCPCH). Wireless communication can also have other common control channels which are transmitted on Common Physical Channels (CPCH). For example, in TDD systems, the Forward Access Channel (FACH) is mapped on the Secondary Common Control Physical Channel (SCCPCH). Both PCCPCH and SCCPCH are examples of CPCH. The same reserved timeslots are typically used throughout a wireless communication system for transmitting the CPCH. It is noted that the term “CPCH timeslot” is used to refer to any timeslot that is used to transmit CPCH in the system.
Depending on the performance of the WTRUs as well as the RF isolation between cells, a TDD type system may be able to only use a single timeslot throughout the system to transmit its CPCH or it may have to use more than one timeslot to allow neighboring cells to use different timeslots and thus ensure good CPCH reception. The use of more than one timeslot to transmit a CPCH throughout a system is referred to as “CPCH timeslot reuse.” On one hand, dedicating a certain number of timeslots strictly for purposes of transmitting the CPCH (i.e. forbidding their use for dedicated channels (DCH)) can lead to inefficient use of the spectrum that in turn translates into capacity loss. On the other hand, reusing CPCH timeslots to transmit DCH signals (i.e. user traffic or DCH traffic) is not done since it leads to highly interfered CPCH signals which could result into CPCH reception problems for WTRUs in some areas. Poor CPCH reception has many negative impacts on wireless communication systems. For example, poor CPCH reception may result in extended time periods for WTRUs trying to access the system, degradation of key radio resource management functions such as handoffs and power control, and service holes for the BCH and FACH.
In currently known wireless communication systems, a certain number of timeslots are dedicated solely for transmitting the CPCH with no attempt to reuse those timeslots for DCHs (i.e. user traffic). Therefore, it is desirable to have a method and system where timeslots used for transmitting the CPCH may be reused for user traffic.